Boiler does not raise pressure

bostonsteam

Hi everyone,
Our building of 8 units has a 4 section Smith steam boiler with a Carlin OIL burner. The boiler will produce according to a tech about 1,292 square feet of steam. Based on the radiators we have, square footage, etc. we need a boiler that can produce 939 square feet of steam (includes 20% allowance for piping). Further, in the same boiler we have connected 2 basement units with a closed hot water loop (baseboard).

Issue 1: The boiler does not produce steam pressure. It goes up to 0.1 psi. It will produce steam pressure up to 0.9 psi if it works continuously for about 1hr.

Solution provided by the tech:
The only thoughts I have are that the steam is getting absorbed too quickly by undersized radiators. Or As you know a lot of the radiators are recessed into the wall. They may be losing radiation into the exterior of the building. I think the right approach here would be to install a boiler 2 sections larger than the existing.

Issue 2:
One of the basement units connected to the closed water loop has low heat (<65F) and the other has high unit (>80F). The one with the low heat controls the temperature for both units through a thermostat in the unit. If the thermostat in the other unit is connected to the boiler then the heat reverses.

Solution provided by the tech:
install zone valves , a zone controller and wiring on each zone . At the same time , purge tees and isolation valves would be necessary.

Can anyone help with these issues? especially issue 1 which is really puzzling to me. The boiler is sized correctly or it appears to be. Is there any STEAM expert in the BOSTON area?

Thank you

KC_Jones

bostonsteam said:

The boiler will produce according to a tech about 1,292 square feet of steam. Based on the radiators we have, square footage, etc. we need a boiler that can produce 939 square feet of steam (includes 20% allowance for piping).

Is 939 the actual measurement of your radiation or is it the radiation PLUS an additional 20%? Either way the boiler is actually oversized for the application. Generally the boiler ratings include a 33% factor for piping already so you compare the boiler rating directly to radiation size without adding anything else for piping. You DO NOT want pressure in a steam system. The pressures you are seeing are great and many people would be jealous you can run so low. If your tech is suggesting a bigger boiler...they don't know what they are talking about and you should find someone who does. The question is why are you worried about the pressure? Low pressure is good high is bad. What issue are you having that you feel the pressure is the problem? Is the building not heating? Uneven heating? As far as a steam expert in Boston I am not sure you could try the find a contractor link on this site. Hopefully someone will chime in on this thread and make a recommendation. As far as the hot water portion...I do not know about those systems, but a little more information would probably help those that do. What type of hot water system? Does it have a secondary heat exchanger or is it using the boiler water directly through the heating loop? Pictures are always a good thing!

bostonsteam

Thank you KC_Jones and MarkS.

Yes the biggest issue we have is that in order for the steam to reach the 3rd floor the boiler must run for very long. If it runs for 20minutes per cycle then I am not getting any heat on the third floor. To get heat it needs to run for more than 40 minutes. and if it runs for 1hr continuously then the radiators register around 197F and are evenly heated.

Note: I have used many vents, from ventrite #1 to varivalve to Gorton.

There is also an issue of uneven heat. The front side of the building has much lower heat than the back side (larger steam pipe). After lots of research, we asked a tech to install main vents at the end of each main steam pipe. This has helped the situation considerably but we still have the above issue.

I will take some pictures for the water loop. I think it takes water from the boiler (it is connected to the boiler) and then it goes to a storage tank, circulator pump, and then to the units.

Thank you

nicholas bonham-carter

Is this a one pipe, or two pipe system?
Have a look at the rating plate on the boiler, and read what the square feet of steam value is there.
I have a million BTU boiler, and I rarely see even 14 ounces.
This must be some sort of main venting problem. For a test, remove the main vents from both mains, and fire the boiler. See if the steam arrives at each end at about the same time. Then add main vents until that timing is duplicated.--NBC

KC_Jones

This definitely sounds like a venting issue which is very common. How much venting is on the main pipes? How long and what size are the mains? With that information we could recommend how much main venting you would need. NBC ask the best question, what type of system one pipe or two pipe? Are the vertical pipes vented (not the radiator vent the actual pipe)? With multistory applications like this it is often beneficial to vent the vertical pipes to ensure that steam arrives at all radiators at the same time. That is the goal of venting make the steam available to all radiators in the building at close to the same time, then vent the radiator slowly and as needed. This is assuming one pipe, with two pipe there are differences depending on the type of 2 pipe system it is.

bostonsteam

Thank Nicholas.

It is a one-pipe system. We installed the main vents in December 2014 but the low steam pressure existed before then.

The steam pipe that serves the units at the back of the building is a big one (3 inches versus 1.5 inch to the front) and the distance where the main vent is to the boiler is shorter. In the back we installed a ventrite #35 (slow vent) and in the front we installed a Gorton #1 Air eliminator (much faster). Further, the steam pipe in the front loops below a steel beam and then goes up. I don't understand how the town inspectors let them do something like this.

The square feet of steam that the boiler produces are around 1292 square feet of steam (375,000 BTU). The tech calculated that we need 939 sq ft of steam which includes 20% additional. For 30% additional, we have 1018 square feet of steam which is still lower than the 1292 that the boiler produces.

Thank you everyone.

KC_Jones

If I am understanding your numbers correctly you have 782 sq ft of radiation on a boiler that produces enough for 1292. So by the steam alone you are about 65% oversized. How big is the hot water portion of this system (BTU's)? You didn't say how long the mains are, but unless they are about 10-15' long you are under vented on your mains for sure. The rule of thumb is a single Gorton #2 vent for every 20' fof 2" pipe. It takes roughly 3 of those #1 vents to equal a #2. You should post pictures of where this main dips under a beam...that could be a problem if it wasn't done correctly. In general you can't have a steam main go down then back up again. the low point will hold water and not let any steam through. It would need some kind of drip line coming off of it to remove condensate.

BobC

My very small steam system has a 12 ft long 2" steam main and I have 2ea Gorton #1's on it and plan to add another at some point. I suspect you need a lot more venting and somebody has to go over all the piping on the problem main to be sure everything is properly sloped and that there are no sags that will pool water and collapse steam. i agree with KC's comment on the dip they did to avoid the steel beam unless they also run a loop over the beam anlong with the dip beneath it.

You also need someone who understands steam, i don't think the guy you use now is really up to speed. Before changing anything, get a knowledgeable set of eyeballs on that system. installing a larger boiler will do nothing but consume more fuel and short cycle. The result will not be cheap but it will pay off in fuel savings and comfort.

JA Phinney is local (Milton) and Charlie from Western Mass might be willing to come east to look at that system.

Bob

bostonsteam

Hi everyone,

I am attaching some pictures of the boiler and the pipes.

In the last picture the big pipe (3 inch?) goes for 30 feet to the back of the building. At that point and before the riser we installed a ventrite #35.

Again, in the last picture, the pipe at the very LEFT (1.5 inch?), loops through the basement unit (inside their walls) for about 45 feet before the riser. That is where we installed the Gorton #1. At some points this pipe has fins around it and there is an opening in the basement unit wall to heat it. It is also this pipe that loops below a steel beam. Of course this type of heating didn't work for the basement units and they installed the closed water loop (see the first 2 pictures).

And yes the boiler produces 1292 square feet of steam and we need 782.

Thank you everyone for your quick responses.

bostonsteam

For the loop below the steel beam, they did put a drip line and that is why it doesn't keep condensate. It is inside the basement unit and I cannot take pictures now.

KC_Jones

The ventrite on that 3" main isn't even close to enough venting for that main. I would start with at least 2 gorton #2 vents and see what that gets you. 2 Gorton #2 vents would equal 20 of those ventrite's. You are MASSIVELY under vented on that main. The other 1.5" main could probably do with a single Gorton #2. These are all starting points you have to see how the system performs then adjust accordingly. Once you do this you will be able to balance the radiator venting. You can't balance the radiators until you get the main venting in order.

SWEI

Only a single tapping used on a 19A-4? Is there enough A dimension there before the drop?

A competent burner tech should be able to downfire that a bit.

KC_Jones

SWEI said:

Only a single tapping used on a 19A-4?

I thought the same thing, but according to the manual on 3-5 section boilers they allow for a single 3" riser. That changes to 2-3" risers when it gets to 6 sections.

Fred

You are way under vented on those Mains. That 3" Main that is 30" long should have at least 3 or 4 Gorton #2's on it. It takes about 3 Gorton #1's to equal the venting capacity of a Gorton #2. The smaller Main should have maybe 2 Gorton #2's at a minimum. All the venting should be at the end of the Mains, after the last radiator run-out or riser to get the best results otherwise they will leave air in the Mains beyond where they are installed Leaving that remaining air to be vented by only the radiator vents, close early, and may stay closed longer than desired.
Once you get the venting on there, you should see a huge improvement.
Do you have any banging in any of the pipes that might indicate steam is hitting water and may be condensing before it can get to the radiators?

bostonsteam

Thank you everyone.

We put the slower ventrite #35 in the 3" main since the back side of the building that it feeds has about 10F higher temperatures than the front side that is supplied by the smaller 1.5" main.

From everything said above, I understand that we need more venting in both mains.

What I still don't get is why it takes 40 minutes or more of continuous boiler run, to receive heat in the top floor and during those 40 minutes the boiler reaches 0.1 psi. If it works for more than 50 minutes continuously then it reaches 0.9 psi and short cycles.

More venting would mean that steam would reach faster in the top units. But is it possible to reach the 0.1 psi in less than 40 minutes?

This boiler consumes as much oil as another boiler of the association which is 1.5 million BTU and serves much smaller units (2000 sq ft less). For instance, this boiler has consumed 3,200 gallons of oil since October 2014, while the other big boiler (recently converted to gas with a Riello RS50 burner) consumed 3,326 therms or about 2,375 gallons of oil (divided by 1.4).

Thank you

SWEI

KC_Jones said:

SWEI said:

Only a single tapping used on a 19A-4?

I thought the same thing, but according to the manual on 3-5 section boilers they allow for a single 3" riser. That changes to 2-3" risers when it gets to 6 sections.

At 310 MBH net output and 1 PSI, I get a bit more than 43 FPS for 3" Sch. 40 pipe. You'd need a 5" header to keep it at 20 FPS.

KC_Jones

What type of gauge are you reading the .1 PSI on? Is it a 0-30PSI gauge or a low pressure gauge 0-3PSI? If it's the 0-30 it's most likely not accurate. Does the boiler have excessive water usage? I only ask to make sure you don't have some kind of leak somewhere which could be causing issues. How often does water need to be added? It is running for so long because you don't have enough venting. The steam can't get in if the air can't get out. Also as I said if you get the main venting corrected and still have issues you may need to vent the risers for the upper floors to speed up the arrival of the steam. Don't worry about the pressure other than trying to keep it low. Higher pressure makes the steam move SLOWER. The lower the pressure the faster it can move...within the limitations of your venting. You are most likely seeing this imbalance because the system is so under vented the steam is trying to move, but venting is hindering it and it just does what it can. Get the main venting fixed then see how it does.

KC_Jones

SWEI said:

KC_Jones said:

SWEI said:

Only a single tapping used on a 19A-4?

I thought the same thing, but according to the manual on 3-5 section boilers they allow for a single 3" riser. That changes to 2-3" risers when it gets to 6 sections.

At 310 MBH net output, I get a bit more than 43 FPS at 1PSI there. You'd need a 5" header keep it at 20 FPS.

I don't disagree, just stating what the Smith manual says. I agree a bigger header would be good. Hey the installer at least did a drop header?! I have a 3" header on my little Weil so yeah on that big boiler more would be better for sure.

Fred

With so little venting on those mains, the steam is spending all of it's energy trying to push the air out so it can get to the radiators. Once you vent those mains properly, you may still need to add a vent or two to the top of the risers that go to the third floor to help get that air out of the system as well but start with the Mains.
Steam is going to take the path of least resistance. You need to balance the mains so that both offer equal steam flow.
The short cycling is a result of pressure building trying to push air when the majority of that time should be supplying the radiators. Of course, the fact that the boiler is so over-sized will contribute to some short cycling but for most heating cycles, the thermostat should be satisfied before the pressure builds enough to start the short cycling.
BTW, where is the thermostat located in this building? Is that area fairly representative of the ambient temp in the entire building?

bostonsteam

I replaced many gauges and attached is the one I currently have. It goes from 0 to 3 psi. I have stayed in the boiler room for many hrs monitoring it. If it starts from cold (boiler has not worked for a few hrs) then it takes about 40-45 minutes to reach 0.1 psi. If the boiler is in the second or third cycle then it takes about 30-35 minutes to reach 0.1 psi.

bostonsteam

Hi Fred,

We have a heat-timer control. There is a sensor outside of the building and another one in the first riser at the back of the building (drip line of the riser). No indoor thermostats.

Fred

Where is the Differential gauge on that Pressuretrol? Also, if this is the only Pressuretrol on the boiler, the Main scale on that pressuretrol should be set down around 1.5PSI. Is there another Pressuretrol on that boiler? Is this Pressuretrol a manual reset? I don't see a reset button.

bostonsteam

Here is the other one (see picture). Picture is shaky but I think it is at 1.5 psi.

Fred

bostonsteam said:

Here is the other one (see picture). Picture is shaky but I think it is at 1.5 psi.

OK. That's good.

KC_Jones

Also what is the water usage like on this boiler? It's hard to imagine that much run time with limited main venting and you aren't getting any pressure....that is unless you have huge radiator vents?

bostonsteam

There is no way to measure water usage on this boiler as we haven't installed any meter.

In terms of vents, the unit ABOVE the boiler room (first floor) has been experiencing the coldest temperatures in all of the building even lower than the units above that unit (in second and third floor). The tech installed Gorton size D in 2 of the radiators and ventrite #1 in the third radiator.

The rest of the building has ventrite #1 throughout, except in my unit where in the coldest and farthest away from the boiler room radiator I installed a Gorton size D.

It is a crazy situation. Last year the heat was better with lower settings on the heat timer and without main vents. This year the heat is lower. I was also looking into quality of oil since whenever they would refill tanks the temperatures were half of what we would normally have. I poured some FPPF HOT 4-in-1 Heating Oil Treatment in each tank. That seemed to have helped somehow.

Fred

You may want to have someone (a Pro) check the burner. It is possible it is not firing like it should, very possible.

bostonsteam

There was a tech that checked it and installed the maximum possible nozzle. He checked the fire and it was good according to him. We also replaced the burner motor last November.

Fred

Is there a filter on the line somewhere that may be clogged? Is the line itself open? Is there any kind of pump/flow controls that may be plugged or failing? If you had good heat last season, something has changed since then.

bostonsteam

Yes there is good supply of oil and we have checked all filters. The tech checked the pressure of oil going in the burner and it was ok. Only the oil itself goes into mind. But I will contact some other Pro to come and check the system.

And responding to your previous question, there is a banging pipe noise in the farthest away from the boiler radiator. I have 5 radiators in my unit and one of them makes this noise.

Fred

Make sure that radiator has some pitch back towards the inlet pipe and that the supply pipe to that radiator is pitched back towards the Main. That should resolve the banging issue but that is not the source of the heating issues. Fix the Main venting and see how far that goes towards resolving the problem (it is absolutely necessary regardless of any other problems). I suspect there may be a fuel supply or burner issue.

vaporvac

How often do you need to replace water, not including a weekly blowdown, if applicable. That's a good indication of any leaks.

bostonsteam

We never replace the water, except when it is cleaned (once a year). I think it gets water on its own through the low water cutoff.

On October 2 different techs told me to release some water from the McDonnell & Miller Low Water Cutoff WEEKLY. I was keep doing it until I noticed that for 1-2 days after releasing water the boiler was producing much less heat. I have stopped for 2 months now and we don't have this issue.

BobC

After releasing water from the low water cutoff, you have to add fresh water to the boiler to get it back up to the normal level. If you don't flush the LWCO it can clog up and not shut the boiler off on low water - that will cost you a new boiler.

Bob

bostonsteam

No one was flushing the LWCO since 2001 that the boilers were installed. I started doing it this year and one boiler was getting flooded and I had to remove water and the other one that has the issues above does not produce heat or produces anemic heat for 1-2 days after the flushing.

The one that was getting flooded I figured out a way to not happen so I keep doing it for it. The water there is dirty. And the tech cleaned that boiler twice last year.

For the one with the issues above, the water comes out relatively clean even if I flush it after 1-2 months.

Thank you.

ChrisJ

Not flushing a LWCO could cost more than a boiler.

It could cost you and others their lives.
Flush the LWCO weekly with the burner running and ensure the burner shuts down!

There is absolutely no reason flushing it would cause less heat even if you didn't refill the boiler, but yes, refill the boiler to the proper level. Do not rely on an autofeeder as it will not maintain the proper water level. An autofeeder is only an emergency backup device to keep the boiler going until you can add water manually.

You should be flushing the LWCOs and maintaining your water levels!

Fred

The water in that sight glass is so, so clear, I have to wonder if it is really representative of what is in the boiler. For a boiler that isn't being blown down weekly, the water should have a little color to it. Are you sure the port tappings for the top and bottom of the gauge fittings aren't plugged up and that maybe the water feeder is only keeping the boiler water at a minimum level that isn't suffecient to produce enough steam to feed the system?

EDIT: I don't even see a shut-off valve on the top of that gauge glass.

bostonsteam

The tappings on the gauge fittings are not clogged. I had the tech check them before replacing one of the gauges. What is clogged is one pipe that comes out of the boiler at the top (behind the LWCO). The tech said that they only use that to release water the first time they install a boiler. Never again.

There is actually a little color in the water. It seems slightly oily to me.

The LWCO are cleaned and checked annually during the inspection and I believe there is a secondary shut off valve according to the tech. As far as the weekly flushing some techs say that it should be done monthly. Introducing more water in the system deteriorates the system much faster. Introducing water weekly through the LWCO might change the Ph of the water in the boiler resulting in my 1-2 days anemic heat as if I remember well these boilers are designed to have a specific Ph.

ChrisJ: How do you add manually water to such a boiler? I rely on the autofeeder until the water goes up to the steam level line. is there another way?

Thanks

vaporvac

OK guys. I'm missing the float LWCO. I just see a probe-type that doesn't normally require a blow-down.
@bostonsteam , many of us here don't use an auto refill, but manually add water. You should be able to shut yours off with a valve, and add water when it goes too low, which it shouldn't unless you have a leak or slow returns. Since you have the auto refill, you might want to look into getting a water meter hooked to it so you can keep track of how much water is being added.

Is that funky piping above the LWCO for skimming or is it some sort of pressure relief? I've never see such a thing.
Colleen

Fred

OK guys. I'm missing the float LWCO. I just see a probe-type that doesn't normally require a blow-down.
That large round device to the right of the gauge glass is a manual McDonnell Miller LWCO with a float in it.
EDIT: If my memory services me right, it is a combo LWCO and auto fill.

Jamie Hall

Changing the pH of the water in the boiler -- provided you don't get it so far off that it foams -- won't affect the steam output. Don't worry about that. Do worry about adding too much water -- you do need to keep track of that.

The major issue is that time to heat. As others have said, that sounds like a main venting problem more than anything else. The fact that you can -- eventually -- build some pressure suggests that if you have a steam leak it's probably not major -- but it's worth looking around, including at the boiler chimney exhaust, to be sure about that. And actually that long to build pressure is not unreasonable -- except that all the radiators in the building should be nice and hot by then.

The chap who said that maybe undersized radiators were absorbing all the steam is a chap to avoid; the comment is so wrong as to be incredible.